Convair A-44

overscan (PaulMM)

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Convair A-44

Artist's conception of the Convair A-44 in flight. Design as of June 18, 1946.
Click to expand...

XA-44, later became XB-53

From http://www.nationalmuseum.af.mil
 

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Could it be that the XA-44 attack aircraft had a less swept wing
compared with the later XB-53 bomber ?
 
From "The vanishing paperclips" by Hans H.Amtmann ,Monogram 1988
and "Les ailes volantes" by Alain Pelletier , ETAI publishing 1999
Engines 3 x General electric J35
Wingspan 24,55 m
Lenght 24,23 m
Hight 7,21 m
Wing surface 127,3 sq m
Max weight 27180 kg
Max speed 938 km/h
Ceiling 13400m
Range 3540 Km
Armament two retractable turrets ,5400 kg bombs and 40 HVAR rockets
 

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I always found the glazed nose curious, since I was under the impression work on this thing started when bombing radars were becoming very popular and a glazed nose was considered obsolete. I remember seeing some "XB-53" drawings that faired it over.
 
Does anyone know if this an XB-53 variant? I found it looking for something else.

Moonbat
 

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lark said:
Could it be that the XA-44 attack aircraft had a less swept wing
compared with the later XB-53 bomber ?
Click to expand...

Lark is correct. The XA-44 design had a forward sweep of about 12 degrees and a dihedral of 3 degrees. The XB-53 had a forward sweep of 30 degrees and a dihedral of 8 degrees. More details to follow.
 
Clioman said:
lark said:
Could it be that the XA-44 attack aircraft had a less swept wing
compared with the later XB-53 bomber ?
Click to expand...

Lark is correct. The XA-44 design had a forward sweep of about 12 degrees and a dihedral of 3 degrees. The XB-53 had a forward sweep of 30 degrees and a dehidral of 8 degrees. More details to follow.
Click to expand...

Waiting eagerly, Clioman!!!
 
XP67_Moonbat said:
Does anyone know if this an XB-53 variant? I found it looking for something else.

Moonbat
Click to expand...

It was General Gavin aircraft;

http://www.secretprojects.co.uk/forum/index.php/topic,5148.0/highlight,general+gavin.html
 
CONVAIR A-44 FACT SHEET

The Convair XA-44 was the original designation for what was later reclassified as a bomber aircraft with the designation XB-53. The aircraft was to have a 30-degree forward swept wing with an 8-degree dihedral. Convair engineers used forward swept wing research data captured from Germany in World War II as the basis for the design. The wing was mounted at the far aft portion of the fuselage and also served as the horizontal stabilizer. The design had a conventional vertical stabilizer and rudder, but changes in pitch and roll were accomplished with wing mounted control surfaces. The elevators were on the inboard wing while the ailerons were outboard. The wingtips were also designed as variable incidence control surfaces.

The design called for three General Electric J35 turbojets of 4,000-pound thrust each mounted within the fuselage. Estimates indicated as top speed of approximately 580 mph. Classified as a medium bomber, the XB-53 would have carried up to 12,000 pounds of bombs. It was also designed for 40 High Velocity Aerial Rockets (HVAR) mounted on underwing pylons.

Convair diverted funding initially allotted to the XB-46 program to work on the XA-44/XB-53 project. Two aircraft were ordered (S/N 45-59583/4), but neither was completed before the XB-53 program was canceled.

TECHNICAL NOTES (as designed):
Armament: 12,000 lbs. of bombs and 40 5-inch High Velocity Aerial Rockets (HVAR); XA-44 designed for 20 .50-cal. machine guns
Engines: Three General Electric J35 turbojets of 4,000 lbs. thrust each
Maximum speed: 580 mph
Range: 2,000 miles maximum
Service ceiling: 44,000 ft.
Span: 80 ft. 7 in.
Length: 79 ft. 6 in.
Height: 23 ft. 8 in.
Weight: 60,000 lbs. (estimated maximum takeoff weight)
Crew: Four
Serial numbers: 45-59583 and 45-59584 (ordered but not completed)



Source: http://www.nationalmuseum.af.mil/factsheets/factsheet.asp?id=3184
 
Also from google;

http://books.google.com.eg/books?id=GmFhOCYckfQC&pg=PA418&dq=MARTIN+xa-15&lr=&num=100&as_brr=3&as_pt=BOOKS&cd=1#v=onepage&q=MARTIN%20xa-15&f=true
 

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What an interesting page with a wide variation of models.
Just a note of warning. As far as I understand these are NASA model numbers, and probably more exactly model numbers assigned by the windtunnel only. As such, they do not represent Convair (or for that matter any other contractor) design or model numbers.
 
You are absolutely right about this, they are NACA model number, I never said they were Convair. You know, I'm sure, that the A-44's/B-53's model numbers are still unknown to this day!

That design's evolution is fascinating indeed. While digging further, I came across a set of even earlier NACA models that seem to have led to it (last one seems Convair, first two look more Northrop):

1940 Tailless Model: http://crgis.ndc.nasa.gov/historic/Additional_Photos_for_12-Foot_Low_Speed_Tunnel_2#Tailless_Model (first five photos only)

Model 32 (first form): http://crgis.ndc.nasa.gov/historic/Additional_Photos_for_12-Foot_Low_Speed_Tunnel_3#Model_.23321 (misidentified as "Model 321")

Model 32 (second form): http://crgis.ndc.nasa.gov/historic/File:1946-1-16_Model.jpg

Model 58: http://crgis.ndc.nasa.gov/historic/Additional_Photos_for_12-Foot_Low_Speed_Tunnel_3#Model_.2358
 
Stargazer2006 said:
NACA Langley archives once again provide much help in understanding the differences between A-44 and B-53. Here are two sets of photos of Models 61 and 74 as tested in Langley's 12-foot Low Speed Tunnel in 1945 and 1947, respectively.

http://crgis.ndc.nasa.gov/historic/Additional_Photos_for_12-Foot_Low_Speed_Tunnel_3#Model_.2361
Click to expand...

Humm, the model 61 seems more related to the fuel transport glider Cornelius XFG-1. Two prototypes completed. One crashed after a spin.

Photo from unknown source.
 

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The 2013 volume of Convair Advanced Designs by Robert Bradley also notes that the XA-44 was also considered for use as a photo-reconnaissance machine and escort fighter.
 
COPY

CONSOLIDATED VULTEE AIRCRAFT CORPORATION

October 21, 1946​

Subject:
XA-44 (XB-53) Airplane
Contract W33-038 ac-7674
Armament Installation

To:
Commanding General
Air Materiel Command
Wright Field
Dayton, Ohio

Attention:
Engineering Division
Bombardment Branch
TSEOA-2

1. This letter will confirm conference this date between Colonel H. E. Warden, Mr. K. N. Scholes of AMC and R.C. Sebold, E.H. Watts and O.H. Snyder of Consolidated Vultee Aircraft Corporation.

2. In brief review, the subject contract was initiated for the procurement of three (3) XB-46 airplanes. During the progress of the contract, our Fort Worth Division prepared a preliminary design study of the XA-44 airplane. The preliminary design study was submitted to AMC for their comments and it was found that the airplane represented an advance type configuration with excellent performance characteristics and appeared to be a very potential weapon. The AMC decided in October 1945 to cancel procurement of the SB-46 airplane and to substitute therefore the procurement of XA-44 model airplanes. Subsequent discussions led to the cancellation of two XB-46 airplanes and the substitution therefor of two XA-44 airplanes. As development of the XA-44 design progressed, the AMC decided to convert this type of airplane to a light bomber. At approximately this same period, a circular proposal was issued requesting bids on a light bombardment aircraft to meet published military characteristics. The XA-44 design, re-designated the XB-53, was submitted in response to the circular proposal, however, since this Corporation could not at that time convert the model to meet all military characteristics, especially defensive armament features, no award was made to us on the light bomber competition. Shortly after an award was made on the light bomber competition, we were requested to submit a quotation covering the modification of the XA-44 design to comply fully with the light bomber military characteristics.

3. This Corporation has exhausted every effort in the design of defensive armament which will meet the military characteristics and will perform satisfactorily on the XB-53 airplane. It has been concluded by this Corporation in agreement with AMC’s Engineering Division, that the present development of defensive armament has not kept pace with the development of high performance airplanes reaching a Mach number of 0.9, and that any defensive armament installation developed to date or which can be developed within the foreseeable future will completely destroy the aerodynamic advancement which has been accomplished in this design. It is therefore our recommendation that the development of this aircraft proceed without the installation of defensive armament.

CONSOLIDATED VULTEE AIRCRAFT CORPORATION​

O. H. Snyder
Dayton Representative​

OHS :ey
 
Colonel Holtoner

10 December 1946
Capt Farry/jm/3563​

Brief Outline of the Background of the XB-53 Light Bomber Project.
Click to expand...
1. The XB-53 is the outgrowth of the XA-44, which was previously changed from the XB-46. The original XB-46 contract, written in March of 1945, called for the procurement of four aircraft. Three were to be flight articles and one a static test article. The static test article was cancelled in June of 1945 leaving the three flight articles on contract at an estimated cost of $10,418,642.19.

2. Under the original 1945 contract, work progressed concurrently with the XB-45 project until it was found that the XB-46 had nothing to offer performance-wise that was not obtainable in the XB-45. Since the XR-45 offered a greater potential for the installation of the equipment, it was desirable to discontinue the XB-46. However, in view of the considerable amount of fabrication accomplished on the first XB-46, it was not considered economical to completely cancel the project. Therefore, in order to take advantage of the aerodynamic information amassed and utilize the contractor’s resources on the XB-46, it was decided to cancel two articles of the XB-46 contract and in their place procure two XA-44’s (of an attack proposal submitted by Consolidated). This change was accomplished in December of 1945 by a change order on the XB-46 contract. One of the main considerations in granting approval for the change order to continue one XB-46 and build two XA-44's, in lieu of two XB-46’s on the unexpended funds of the original contract, was the fact that Consolidated stated that they could deliver the same number of airplanes with increased amount of data and mock-ups contemplated originally. The increased amount of data and mock-ups included additional research and development for two separate jet bombers. It represented an expenditure of only $650,000 more than the cost resulting from the stoppage of the XB-46 contract and the procurement of three XA-44 airplanes. It was further stated that the $10,418,642.19 plus the $650,000 would be the maximum cost and would probably be reduced when cancellation charges of the two XB-46’s were considered.

3. In June of this year, another change in this project was proposed. This was to convert the XA-44 to a light bomber to be known as the XB-53 at an additional cost of approximately $1,260,177. This change was favorably considered since there no longer existed military requirements for the attack airplane and it also involved a change in the sweep of the wings from 12° to 30°, which increased high speed of 64 mph and a cruising speed of 87 mph without a sacrifice in range.

4. The total authorized expenditure of the above amounts to approximately $12,328,800. This, in addition to the present request for $7,435,543 to complete the XB-53 contract, makes a total of approximately $19,764,370 which is about $8,000,000 more than the original contract of the XB-46.

5. Originally the change order on the XB-46 contract was conceived to secure an airplane of a more advanced design and thereby effecting a more economical use of government funds previously obligated. However, the result is an airplane comparable to the XB-51 at a much higher cost. Therefore, it is recommended that the XB-53 project be discontinued.

ALBERT B. FARRY
Capt., Air Corps
Bombardment Section​
 
HEADQUARTERS
ARMY AIR FORCES
AIR TECHNICAL SERVICE COMMAND​

IN REPLY ADDRESS BOTH
COMMUNICATION AND
ENVELOPE TO ATTENTION
OF FOLLOWING OFFICE SYMBOL:
TSENG (TSESA2)

TSESA2/EGN/bg

WRIGHT FIELD, DAYTON, OHIO

15 November 1945​

SUBJECT: Procurement of Bomber Type Airplanes.

TO: Commanding General,
Army Air Forces, Washington 25, C.
Attn: ACAS-4

1. This Command has been currently carrying out preliminary negotiations with Consolidated-Vultee Aircraft Corporation for the design and development of an Attack Bomber designated as XA-44. The discussions have been carried on with a view toward obtaining the greatest amount of development consistent with the availability of funds. The Contractor has agreed to carry on the work on a fixed price contract.

2. Insofar as the straight wing jet propelled medium bomber is concerned, it is felt that this type is amply covered by existing contracts with North American and Glenn L. Martin Company, for the XB-45 and XB-48 airplanes. Accordingly, it was considered advisable to cancel the XB-46 and use the funds for the procurement of the XA-44 airplane, which subject has been previously discussed by the Chief, Engineering Division and ACAS-4. However, at a recent conference held between the General Manager, Consolidated-Vultee Aircraft Corporation, and the Chief, Engineering Division, it was pointed out that a considerable amount of work has been accomplished and a great deal of money has been spent on the XB-46 contract. Accordingly, it was proposed by the Contractor to complete one (1) flight article XB-46 and design and develop two (2) flight articles, XA-44 on a fixed price contract, all for the present amount of money set up on the XB-46 Letter Contract. The Contractor will not proceed with the actual fabrication and construction of the XA-44 airplanes until Phase I is essentially completed and the entire project has been entirely reviewed. Following this procedure will permit obtaining an Attack Airplane essentially in agreement with Military Characteristics of 25 July 1945.

5.The XA-44 airplane is considered to be one of the cleanest designs presented to this Command for a tactical airplane. Brochures describing this airplane have been distributed to your office and to the office of ACAS-3 by the Washington representative of Consolidated Vultee Aircraft Corporation. Estimated performance data for this airplane are as follows:

High speed, sea level
561 mph

High speed, 13,000 ft.
583 mph

Tactical operating radius 5,000 ft. Alt. to and return from target at 58,000# gross weight
535 miles

Tactical operating radius 5,000 ft.. Alt. to and return from target at 64,000# gross weight and with wing tip tanks
691 miles

Service ceiling, 58,000# gross weight
44,000 feet

Take-off over 50-foot obstacle, 58,000# gross weight, no auxiliary thrust
5,900 feet

Take-off over 50-foot obstacle, 64,000# gross weight, no auxiliary thrust
7,600 feet

12 Fixed forward firing guns, .50 cal.

8 Flexible guns, turret mounts, .50 cal.

Note: Maximum bomb load of 12,000# can be carried internally. Radar ranging for offensive armament and radar scanning for control of defensive armament.

4. In view of the extremely desirable development program and the best utilization of funds, it is requested that the plan and procedure discussed with Consolidated-Vultee Aircraft Corporation for retention of one (1) XB-46 and procurement of two (2) XA-44 airplanes be approved.

FOR THE COMMANDING GENERAL:​

/S/
L C. CRAIGIE,
Brigadier General, U. S. A.
Chief, Engineering Division​
 
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riggerrob said:
What did a on air know about gunners’ periscopes that Avro did not. Early in the production run (early 1940s) Avro tried installing belly turrets controlled through periscopes on early Lancaster heavy bombers. When they proved ineffective, they were deleted.
Click to expand...
Was probably based on the B-29's remote sighting system, which was complex but supposedly worked really well.
 
riggerrob said:
What did Convair know about gunners’ periscopes that Avro did not?
Early in the production run (early 1940s) Avro tried installing belly turrets controlled through periscopes on early Lancaster heavy bombers. When they proved ineffective, they were deleted.
Click to expand...

Gunners' periscopes worked quite well in German aircrafts; the PVE 11 being the most refined intended for the Ju 388.
 
While talking remote turrets, remember the B-17 had a remote ventral turret for a time,

B-17E Remote Turret: Bendix or Sperry? - Aero Vintage Books

A history of the development of gun turrets for the B-17, including an answer to the question: Bendix or Sperry remote lower turret on the early B-17Es?
www.aerovintage.com www.aerovintage.com

This is a bit of an old subject here at Aero Vintage Books, but I thought it worth revisiting. The first B-17Es rolled from the production line with a remotely-operated lower turret installed just aft of the radio room on the belly of the B-17. It had a shape and size similar to that of the new top turret installed just aft of the cockpit.

A look at many B-17 information sources, be they magazines or casual books, or even authoritative reference books on the airplane, speak of the first version of this lower (belly) turret as being a “Bendix” turret. Even one of my author/photographer heroes, Peter Bowers, does so in his excellent 1976 book Fortress in the Sky.

But, no. It was clearly a Sperry remote turret installation. Bendix had nothing to do with it. It did not retract and it was operated by a gunner lying prone in the fuselage aft in the turret with a gun sight that protruded into a plexiglass bubble on the belly, with six added viewing windows to help the gunner identify attacking fighters.

As can be seen in paragraph (4)(a) below as extracted from a B-17E technical order, the “Sperry number 645705-D remote sighted twin .50-caliber bottom turret” was installed on the first 112 B-17Es that rolled from the Boeing factory at Seattle beginning in November 1941…serials 41-2393 through 41-2504 inclusive.
Click to expand...

Additionally,

inchhighguy.wordpress.com

The Boeing B-17E and the Myth of the Bendix Ventral Turret

If you are planning to model one of the Hawaiian Air Depot scheme Boeing B-17E Flying Fortresses, or any one of the first 112 B-17Es produced for that matter, something which will have to be dealt …
inchhighguy.wordpress.com inchhighguy.wordpress.com

The Sperry number 645705-D was also remotely sighted, but the sighting periscope was located aft of the turret in a clear blister. The gunner was also provided with six small scanning windows, two square windows on the underside of the fuselage, and two rectangular windows on each fuselage side. The Sperry remote ventral turret was constructed using the same structural elements as the manned Sperry dorsal turret but without the clear perspex panels.

Neither remote turret was successful. Crews reported difficulty in acquiring and sighting their targets. Mechanical reliability was also an issue. Gunners using the Sperry remote turret often became nauseous due to having to lay prone facing aft to use the sight. Many crews decided the turret was not worth the weight and deleted it entirely or replaced it with the manned Sperry ball turret at the first opportunity. No kills were recorded by gunners using the Sperry remote turret.
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Hammer Birchgrove said:
It looks like it could use canards and a three-way fly-by-wire system. ;) :p
Click to expand...
You are proposing complex solutions to simple problems.

It is possible to build a stable flying wing or even forward-swept wing without an sort of artificial, electronic fly-by-wire stability augmentation system.
See the Cornelius gliders of World War 2.
All the Fauvel and Backstrom flying planks (tail-less, flying wings with constant chord and zero sweep) depend upon balance and natural stability. Fauvel's later tail-less glides had tapered wings with straight leading edges, hence they had mild forward sweep.
Marske was inspired by the earlier works of Fuavel and Backstrom. Marske's first glider was a flying plank based upon Backstrom's works but all of Marske's later gliders (Pioneer, Monarch and Genesis) vhad forward-swept wings.
The key to pitch stability is mounting the center-of-gravity forward of the center of lift .... the same as conventional tailed airplanes and even Rutan's canards.
 

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